Just like you can hold down the back button in Safari, Firefox, or Chrome, holding down the Finder's back button in Lion shows you where you've recently been.

This only works in Lion, unfortunately, but it's a really useful shortcut if you want to go back two or three folders instead of just one. It isn't a mind-blowing feature that's going to make the Finder any less bare, but it's one we didn't know about and can come in pretty handy.